Zeilin, Jacob was born on July 16, 1806 in Philadelphia, Pennsylvania, United States. Son of Jacob Zeilin.
Attended United States Military Academy.
Second lieutenant United States Marine Corps, 1831. Served in ship Erie off Brazil, 1835-1837. Promoted First lieutenant, 1836.
Served aboard Congress in Mexican War, served in landings in California and Mexico. Brevetted major, 1847, promoted captain, 1847. Marine officer of E. India Squadron under Matthew Perry, served on ships Mississippi and Susquehanna.
Wounded at 1st Battle of Bull Run. Promoted colonel, 1864. Commandant of Marine Corps, 1864-1876.
Promoted brigadier general, 1867, retired, 1876.
Married Virginia Freeman, October 23, 1845, 3 children including William F. Commissioned.